The temporal association and mechanisms contributing to the link between depression and obesity remain elusive. This lack of knowledge is a significant problem; until additional data become available, successful primary and secondary prevention efforts will remain difficult to design and implement during the crucial time of childhood and adolescence. The candidate's long-term goal is to develop an independent research career in the area of behavioral neuroendocrinology with a specific focus on the pathophysiologic components that define the association between depression and obesity in children and adolescents. The scientific objective is to identify mechanisms by which depression and obesity are associated. The central hypothesis is that depression and obesity are temporally associated, share common pathophysiologic factors, and subsequently interact to promote advanced disease status in both disorders. The rationale for the proposed research is that once it has been completed, effective primary and secondary prevention programs for adolescent-onset depression and obesity can be formulated. This proposal will also allow the candidate to establish herself as an independent investigator in the areas of depression, obesity, and behavioral neuroendocrinology. The research will utilize longitudinal data from two completed NIH-funded studies of girls during two important developmental stages, school age and adolescence. The proposed pilot study will carefully evaluate neuroendocrine factors (i.e., hunger/satiety hormones, stress response, metabolic factors), maladaptive thoughts (i.e., body dissatisfaction, self-efficacy), and eating behaviors (i.e., emotional eating, binge eating) among adolescent girls with and without newly diagnosed Major Depressive Disorder (MDD). Girls will be followed for one year to assess the relationships between depression, neuroendocrine factors, and maladaptive thoughts and eating behaviors with changes in weight (i.e., obesity). Along with an improved understanding of any temporal associations between depressive symptoms and obesity, the contribution of the proposed research includes an evaluation of whether neuroendocrine hormones regulating hunger and satiety, maladaptive thoughts, and eating behaviors are differentially affected in girls with and without MDD. The research is novel in that it integrates knowledge from the field of obesity with the study of adolescent depression. This application has the potential to provide insightful information to guide prevention and intervention strategies for the two emergent health problems of depression and obesity among youth. Last, the application will enhance the candidate's skills in complex longitudinal analyses, clinical and research approaches to adolescent depression, assessment of neuroendocrinologic and psychobiologic markers, measurement of psychological constructs (i.e., maladaptive thoughts and eating behaviors), and behavioral theory and interventions related to depression and obesity. These skills will significantly advance the applicant's research program in this problematic area of child and adolescent health.